Automotive vehicles deliver input torque to a transmission from one or more torque sources, typically an engine and/or one or more electric machines. The level of input torque is based on a torque request as applied by a driver to an accelerator pedal. Transmission output torque is transmitted at a controlled level to drive axles of the vehicle. When the torque request remains unchanged for an extended period of time, a powertrain controller can assume that the powertrain is providing sufficient output torque. Control actions may be executed by the controller under such conditions, such as selective cylinder deactivation, in order to optimize overall fuel economy. In this mode, instead of following the driver's torque request, the controller can command that transmission output torque instead pursues a calculated optimal output torque target.
In a hybrid powertrain in particular, a high-voltage battery energizes the electric machine(s) for the purpose of motor torque generation. The motor torque can be used to propel the vehicle in electric powertrain mode, or to assist input torque from the engine. The state-of-charge, electrical current, and individual cell voltages of the battery may be monitored over time against allowable maximum and minimum battery power limits. Commanded output torque may be automatically determined by evaluating the driver torque request against such battery power limits, as well as limits on engine torque, motor torque, clutch torque, and/or other powertrain constraints. Available power from the energy storage system may be converted into an optimal output torque or crankshaft torque, which may be used as a target in open-loop control logic. A similar approach may be used for conventional powertrains that forgo the energy storage system and the electric machines noted above.